looking for help on multimonitor setup

[Fungal-net]

> have you run xrandr to see what modes the external screen is offering - which
> is claims is native etc.?
> ------------- Codito, ergo sum - "I code, therefore I am" --------------
> Carsten Haitzler - raster at rasterman.com


This is pretty much the answer I would have given as well, if xrandr doesn't show your expected resolution in the list then either the monitor is not recognizable or not sending adequate firmware/identification. Possible glitches can be connectivity, vga, hdmi, dp, dvi-d ..etc.

Also, is the monitor plugged before boot or after? It does make a difference with some connectictivity combinations.

Same monitors connected via different port behave/identify differently.

For those who get frustrated in the terminal formatting a proper instruction there is the arandr gui that works anywhere X is running. It is like the gui side of xrandr, it will even work when starting a terminal without a wm. You visualize how you want the setup arranged and save it into a script. Then look at the script it saved, that is the proper xrandr command that you can add to some autostart script on your wm/dt
Most of the headaches I've discovered are cables that are also adapters of one connection to another, as well as tv (spec) used as monitors faking actual resolution and/or size.
I don't think there are DTs that can't comply with this because even the oldest most abandoned WMs I'v tried all work with xinerama support. But you are confusing using multiple monitors issue with the issue of properly identifying it.

Similarly on wayland there is wlr-randr but in my experience what you get on X you get on wlr